Abstract This work reports the Vapour‐Liquid Equilibrium (VLE) data, at 78 kPa, for a HCl‐ethanol‐water ternary mixture at low HCl content (x ≤ 0.137, which corresponds to HCl usual commercial form). The data were adjusted using the electrolyte‐NRTL activity model. The obtained predictions presented an absolute average deviation of 0.853 %. Next, this model was used to construct the residue curve map of the HCl‐ethanol‐water mixture. The analysis of its topology provided a fundamental understanding of the ternary mixture behaviour upon distillation process. Four different separation regions were identified. Finally, based on the residue curve map, a distillation column was designed to accomplish three design constraints: HCl‐water commercial product composition, maximum ethanol recovery for recycle, and minimum energetic duty in the reboiler.